Tiling concrete floor and UF heating

[Flintstone]

Double post

 

[Flintstone]

The key lesson here steve is to do the job properly from the ground up with a reputable tiler who knows what he's on about. The uncoated boards are not the cause of the problem neither is the fact they were not primed. Yes they are inferior but they are still suitable if used correctly

 

[Bathfix Bob]

If nothing else please say they are porcelain tiles?

 

[The Tiler]

thanks Steve
the floor prep wasn't right, needed SLC
imho the second error was not priming the boards underside.

a new tiler should not continue with this install as what he is tiling onto is not sound.
the areas of failure are small, may get bigger, time will tell.
I would be surprised if tiling over these areas doesn't give you an a floor you are happy with but that something between you and your fixer to talk about.

 

[The Tiler]

Foil coated, gypsum based boards are available for wet underfloor heating. You can argue with me until you are blue in the face, you do not need to prime the back of bare foam boards or the cement coated ones. Regardless of what ultra say on that bumf you have posted ! Priming the face of cement coated is best practice for SLC.

I'm not here to go blue in the face! I'm asking questions and passing on my knowledge which I believe to be correct unless I'm shown to be wrong, may will happen
as for foil covered gypsum boards I wouldn't touch for any reason. Is there a thread you can point me to on how to fix to these please.

 

[Spare Tool]

Ive fixed those un-coated boards a few times and never primed either side of em yet..just stick them with a wetter mix of adhesive making sure not to trap any air pockets under them. The problems here have come from trying to stick them to a floor that wasn't leveled over in the first place..

 

[The Tiler]

hi Andy
not looking for argument on the subject and maybe getting of topic as harry said, but why prime top and not bottom? Both are stuck with adhesive

 

[hmtiling]

hi Andy
not looking for argument on the subject and maybe getting of topic as harry said, but why prime top and not bottom? Both are stuck with adhesive

I wouldn't use them again but priming the top would help the ufh adhere properly and prevent any curling and also aid flow of levelling compound

 

[Dumbo]

I haven't found a background yet that priming is detrimental . No need to prime and do not under any circumstances prime are two different things. But i havent used those cheap uncoated boards

 

[The Tiler]

looks like I'm out number but will still prime both sides as I believe it should be, have seen how bad a S1 adhesive sticks to an unprimed surface and sadly not found another product I'm happy using for wet heat. As for electric I'd use a covered backer board.
looking forward to reading other posts and giving input if I think it will be of assistance, please be gentle with the newbe

 

[Andy Allen]

I haven't found a background yet that priming is detrimental . No need to prime and do not under any circumstances prime are two different things. But i havent used those cheap uncoated boards

Depends on the adhesive being used.
Some state do NOT prime cement boards or light weight backer boards...

 

[Dumbo]

Depends on the adhesive being used.
Some state do NOT prime cement boards or light weight backer boards...

I've had that before . One which springs to mind was bal saying that about ply ( not that I was tiling to ply ) but it was in a similar conversation to this . So rang them up and challenged them over it ( I particularly like challenging bal self proclaimed messiah's of tiling ) and their response was you can prime it if you want to without affecting performance .

 

[Steve01]

If nothing else please say they are porcelain tiles?

Yes polished porcelain - what difference does that make ?

 

[Andy Allen]

I've had that before . One which springs to mind was bal saying that about ply ( not that I was tiling to ply ) but it was in a similar conversation to this . So rang them up and challenged them over it ( I particularly like challenging bal self proclaimed messiah's of tiling ) and their response was you can prime it if you want to without affecting performance .

This is taken from there pdf, the adhesive is bal single part fast flex, an adhesive I use all the time on wooden substrates with cement boards...

 

[Dumbo]

Right if you look at next paragraph down that is what I challenged them on. Saying do not prime surfaces to be tiled on . I challenged them and they ok not a problem . So I wouldn't rely on that . I've not finished bal tech will get a call from Mr pain in the arse from salisbury